The present disclosure is directed to a multilayer film with a core component containing particulate filler material, the multilayer film suitable for MAP.
Improving the quality and the shelf life of fresh produce and fresh cut produce has long been an objective of the food industry. Technologies such as controlled atmosphere storage (CA), modified atmosphere packaging (MAP), and ripening control technologies such as ethylene absorbers and ethylene antagonists (1-MCP) have been developed and are selectively used to achieve extended produce shelf life and improved produce quality. Understanding of biological variation such as fruit type, variety, maturity, growing region, and climatic response are key when selecting the appropriate technology for packaging, storing, and transporting produce.
Most produce incurs significant damage from fungus and mold when the moisture level inside a package is too high and condensation occurs. Most produce incurs significant damage when the moisture level inside a package is too low and dehydration resulting in shrivel occurs. Most produce generates carbon dioxide (CO2) as it ripens and consumes oxygen (O2). Most produce incurs damage when the CO2 level in the package becomes too high (typically above 5%). Thus, the art recognizes the challenge in producing a MAP-package for produce that achieves desired levels of transmission for four gasses—O2, CO2, ethylene, and 1-MCP and simultaneously maintains suitable water permeability.
Conventional monolithic MAP has shortcomings. Conventional MAP typically provides one desired permeation feature at the sacrifice of other permeation or transport features. MAP films made from polymers with high water solubility such as nylon or polylactic acid have high water transmission rates and are often used for produce that is moisture sensitive. These polymers typically are good barriers to other gases such as carbon dioxide, oxygen, ethylene, and 1-MCP which can be harmful in some the applications. Moreover, these high water solubility polymers are expensive relative to polyolefins.
On the other hand, MAP films made from polyolefins typically have good transmission of ethylene and carbon dioxide but have low water transmission rate. The olefin polymers are typically low cost and also offer good toughness, transparency, heat sealing, and processability.
Perforation also has shortcomings. Although perforation (either micro-perforation or macro-perforation) can increase the oxygen transmission into the produce package, it requires additional processing steps and additional processing equipment, therefore adding energy and cost to the film. In addition, perforations may increase oxygen transmission for a film but they do not provide significant amounts of water transport unless the perforations are very large (˜3 microns or greater). Perforations also move less carbon dioxide than oxygen at equivalent driving forces due to the higher molecular weight and slower diffusion of carbon dioxide (Graham's law). Perforations can create a natural carbon dioxide accumulation in produce packages made from low carbon dioxide transport films such as nylon, for example.
A need exists for a film capable of balancing transmission of one or more gasses in conjunction with maintaining water permeability suitable for produce packaging applications. A need further exists for a produce packaging film with suitable CO2 transmission, the ability to transmit ethylene and 1-MCP, while simultaneously providing controlled water permeability to enable the benefits of the MAP environment.